<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>十字架小icon</title>
</head>
<body>
  <div class="add">
  </div>
  <style>
    .add{
      position: relative;
      width: 120px;
      height: 120px;
      margin: 200px;
      color: #ccc;
      border: 1px solid;
      transition: color .5s;
    }
    .add::before,.add::after{
      content: "";
      width: 60px;
      height: 60px;
      position: absolute;
      left: 50%;
      top: 50%;
    }
    .add::before{
      margin-top: -5px;
      margin-left: -30px;
      border-top: 10px solid;
    }
    .add::after{
      margin-top: -30px;
      margin-left: -5px;
      border-left: 10px solid;
    }
    .add:hover{
      color: red;
      cursor: pointer;
    }
  </style>
</body>
</html>